The invention relates to optical fiber couplers and more particularly to optical fiber couplers which are mountable.
In order to connect one optical fiber to another, the fibres to be connected are equipped with connectors at their ends. There are many types of such connectors, the most commonly used in North American telecommunications applications being ATandT""s (American Telephone and Telegraph) ST-type connector, and NTT""s (Nippon Telegraph and Telephone) FC-type connector. Two fibres which are to be connected are equipped with the same type of connector (FC or ST), and these connectors are each connected to an intermediate optical fibre coupler (sometimes referred to as a coupling receptacle in the case of like connectors or a coupling adaptor in the case of connectors of two different types). A common requirement for any interconnection of optical fibres is that the connector ferrules be cleaned periodically because even a small amount of dust can interfere with optical signal propagation.
It is common to employ optical fibre couplers mounted in a panel forming part of an equipment enclosure thereby facilitating the interconnection of an external optical fibre to an internal fibre inside the enclosure connected to other internal equipment. There are several problems with the available techniques for mounting such optical fibre couplers. Such optical fibre couplers are typically mounted in a hole in the panel with a pair of screws which are difficult to undo. Even after such screws are removed, and the optical fibre coupler is removed, the internal fibre and its connector is still inside the enclosure and it is difficult to access the connector through the hole in the panel because such holes are conventionally smaller in diameter than the diameter of the connector terminating the internal fibre. This makes it very difficult to clean the connector of the internal fibre.
To alleviate these problems special design enclosures have been proposed (see U.S. Pat. Nos. 5,127,082 to Below et al which issued Jun. 30, 1992, 5,613,030 to Hoffer et al which issued Mar. 18, 1997) and optical fibre buildout systems have been proposed (see U.S. Pat. Nos. 5,067,783 to Lampert which issued Nov. 26, 1991, 5,717,801 to Smiley which issued Feb. 10, 1998, 5,073,042 to Mulholland et al which issued Dec. 17, 1991, and 5,274,729 to King et al which issued Dec. 18, 1993). These solutions are not very cost effective.
It may also periodically be a requirement to remove such an optical fibre coupler from a panel in order to replace it with a different type of optical fibre coupler, or to insert a bulkhead fibre optic attenuator for example. This task is also made difficult by conventional optical fibre coupler mounting techniques.
It is noted that both FC and ST-type connectors rely on a ferrule to achieve precise fibre alignment, but they employ different and incompatible latching mechanisms. The ST-type connector relies on a xc2xc turn bayonet (spring loaded twist and lock) coupling mechanism, and the FC-type connector relies on a threaded coupling mechanism. In order to interconnect two fibres which are terminated with different connector types, for example an FC-terminated fibre and an ST-terminated fibre, special adaptors are required.
The most commonly used fibre connectors in local area communications include the SC-type connector and the above identified ST-type connector. Again, these connectors use different and incompatible latching mechanisms with the ST-type connector relying on the above identified xc2xc turn bayonet coupling mechanism, and the SC-type connector relying on a push-pull coupling mechanism.
Applicant""s copending U.S. application Ser. No. 09/019,508 Filed Feb. 5, 1998, hereby incorporated by reference, discloses couplers to facilitate the interconnection of different connector types.
It is an object of the invention to provide a mechanism for mounting optical fibre couplers which facilitates their removal.
According to a first broad aspect the invention provides an optical fibre coupler mountable to a panel surface having a central hole, the coupler comprising: a first receptacle capable of receiving a first optical fibre connector of a first type; a second receptacle capable of receiving a second optical fibre connector of a second type, the first and second receptacles providing an optical interconnection between the first and second optical fibre connectors when connected; a bushing between said first and second receptacle having a mating surface on a side towards said first receptacle for abutment against the panel surface; at least two parallel pins permanently mounted in said bushing which extend from said mating surface; whereby the coupler is mountable to the panel by inserting the first receptacle through the central hole and by inserting and frictionally removably retaining the at least two pins in pin receiving holes correspondingly located on the panel.